Saturday, March 11, 2017

Propagation Sanity Check

This morning we received an email from Finland!  It's always nice to hear from our "neighbors" across the north pole.  I know we share a common bond when it comes to tough propagation.

Hello, Sirs.
It is quite foolish to ignore JT65 spotter on.
The whole of Europe called on you.

None of the answer does not come from there.

OH4SS, Matti

I was certainly sorry to miss the opening.  

So it would seem Matti is implying one shouldn't run JT65 spots to PSK Reporter if not in the shack. Now that's an interesting point of view, and one I haven't encountered before.  I think we have a little disagreement here with Matti, but maybe there are others out there who feel the same way. 

"Foolish"?  Let me explain my rationale.

Followers of the blog -- are there any? -- will know there are special challenges the ionosphere lays on us in the high latitudes.  What they teach you in radio school about propagation being basically reciprocal is total nonsense above 60 degrees or so.  It's actually hard to figure out when openings may occur.  The second element to this puzzle besides geomagnetic instabilities is the rapidly changing daylight in the Far North.  In Fairbanks, daylight changes 6-7 minutes per day throughout much of the year.  That has huge implications for HF, as one week is literally completely different from the next.

Sooooo...here at KL2R we make frequent use of spotting software and other tools to monitor the bands. That includes CW Skimmer reporting to RBN and WSJT-X reporting to PSK Reporter.  The data is helpful to other hams who are anxious to see when the bands are open to Alaska.  What's not to like?

The other reason we frequently run receivers and spotting software when the shack is unattended is to gather data for serious technical analyses.  The data sets are useful for comparing station performance, for instance.  JT65 actually yields quantitative results on received signal-to-noise ratios from various locations.  We can compare, say, AL7ID just a few miles away.  Even better, years of study have clearly demonstrated the myth of reciprocal propagation.  Approximately 80% of the time, the KL2R signal SNR will be about 6-10 dB worse at the remote station than received here.  What that means in practical terms is that when we receive JT65 at around -15 dB (good by most standards), the other station is likely to receive us at very marginal levels, if at all.  So there you have it.

Finally, let me just say presence on PSK Reporter is not the same as a call for CQ.  The spotting network does not substitute for actual RF.  So who's "foolish"?  I suggest those who would call a station without hearing their signal.  Whatever the mode, many Europeans have a bad habit of throwing out their callsign into the ether in the hopes the DX will log them, like a message in a bottle. It's remarkable that within hours of working a pileup I will get requests by email, like "Please tell me if I worked you."  Seriously?  If I worked you, you would know it.

Friday, March 3, 2017

Experience with SDRs

A couple of years ago, N1TX was sufficiently impressed with the QST review of the FiFi SDR from Germany to order a kit and put it together.  After experimenting with it as a standalone receiver, an RF Space IF-2000 board was added to one of the FT950s.  The FiFi then became an integral part of operations, providing bandscope functions and feeding VE3NEA's CW Skimmer.  HDSDR was used to drive the FiFi, and HDSDR was kept in sync with the logging and CAT software through Omnirig.  It proved very effective, and a second FiFi was added to the FTdx-5000MP.  No interface board is required, since the FT5k radio has an IF output port.  The guidance provided by G4ZFQ was invaluable to setting everything up.

The FiFi is a "sound card" SDR and a good entry-level package.

Of course, while the FiFi, SDR-Play,  Soft Rock, and others like it are somewhat plug-n-play, soundcard-type SDRs have inherent limitations due to the way frequency conversion and filtering are implemented.  Note I said "somewhat plug-n-play".  The need to tweak multiple parameters to derive optimal performance and calibration can be a pain.  

Enter Brad Forker KC7JLU, who contacted us in 2016 to discuss installing a remote SDR in Fairbanks.  I was intrigued by a system set up so anyone in the world could tune in to the Alaska receiver via the internet and sdranywhere.com. Soon the CloudIQ was delivered from RF Space and connected to the KL2R antennas.   

The stand-alone “Cloud” mode includes a built-in internet server. In this mode, the radio performs the tuning and demodulation of signals and transmits the demodulated information back to a PC, OS-X, Linux or Android client anywhere in the world.  Control, display, and audio information can be supported over a modest internet connection.  There were few issues with streaming and control, which was used to great success during KL7FWX Skywarn on-air activities in December.  Lower noise levels and better antennas at KL2R yielded positive results. Download the RemoteSDR client to listen. Note: The unit is now on an amplified loop antenna at WL7CW's hilltop location.

A few brief experiments with the SDR in IQ mode were very convincing.  In this mode, the CloudIQ streams raw 24-bit IQ data at 1.8 MHz to software like SpectraVue running on a machine on your LAN.  Wired and wireless rates are sufficient, but streaming this amount of data over the internet may not succeed. (Hence, the Cloud mode).  However, run on the local network as either a stand-alone receiver or IF receiver, CloudIQ adds some powerful capabilities.  Having a completely independent, wideband receiver in the shack is advantageous.  Driving a radio these days without a bandscope is like flying blind.  Spectravue also allows for synchronization to a local PC-controlled transceiver for true point-and-click ability to select frequency, bandwidth, and mode settings.  We added a second CloudIQ to the FTdx5000 as an IF receiver.  It works great with the FT950 + IF-2000 as well.

One thing not tested yet with the CloudIQ is CW Skimmer.  The FiFi feeds IQ data via HDSDR into a VB-Audio virtual audio cable "connected" to the skimmer for monitoring 24 kHz bandwidth.  It is not clear from brief internet searches how to feed IQ data from CloudIQ.  Another concern is whether or not it is possible to maintain the SpectraVue bandscope function with point-and-click tuning while operating in skimmer mode due to port limitations and conflicts.  Even without CW Skimmer, it's a nice asset during the contests.


Wednesday, February 22, 2017

A new KL7 QRP Record


Where Have All the Signals Gone?

One of the main reasons you haven't heard KL2R much lately is the totally abysmal propagation plaguing us at the high latitudes for months and months.  That coupled with a short summer filled with rain, which hindered any attempt to do major station work outdoors.  There's still that other tri-bander to get up, a 160 vertical to repair, and 80m vertical system...Oh, and WARC antennas to build. And to boot, we're engaged with the North Pole Contest Group to keep KL7RA on the air, plus upgrades.  We've made a few appearances in CW and RTTY contests this winter, but all in all, activity has been very limited.

So let's have a look at a few factors influencing our ability to reach out from the high latitudes. According to my observations in nearly 20 years in Fairbanks. geomagnetic instability results in horribly fickle radio conditions.  The planetary K index (Kp) is used to characterize the magnitude of geomagnetic storms. It is measured on a scale of 0 to 9.  K-indices of 5 or higher indicate "storm-level" geomagnetic activity. Values of 7 or higher indicate a severe geomagnetic storm.  However, when Kp > 3, we at 65 degrees north have one heck of a time getting out.  We hear stations, but they often do not hear us.  This is particularly true on 20-10 meters.  The turbulence in the ionosphere will open the window for a couple of minutes and then shut for many more.  On 80 and 160, a Kp of 1 or 0 is acceptable, although such conditions are very rare.  The ups and downs are frustrating to say the least.  Nevertheless, it teaches patience.  The effects are less severe at lower latitudes, even in Anchorage or Kenai, which are near 61 degrees north.


When the aurora kicks up, which is associated with a high Kp, absorption is obviously the problem. We can often work stations within the auroral oval; e..g, UA0 or Scandinavia, but getting to W7 is problematic.

A lot of hams religiously watch the planetary A index, or Ap.  The Ap is a measure of the general level of geomagnetic activity over the globe for a given day. A mean, 3-hourly “equivalent amplitude” of magnetic activity based on K index data is computed from 11 Northern and 2 Southern Hemisphere magnetic observatories between the geomagnetic latitudes of 46 and 63 degrees.  For that reason -- the limit of 63 degrees -- the Ap is less applicable to Fairbanks at 65.5 north geomagnetic.  Even better, data from the College, Alaska, observatory are good real-time indicators of conditions.  See plots at the feed for the College Observatory (CMO).  If you are wondering where Alaska is in the contest, you might have a look at this and NOAA's Space Weather Prediction Center, which has an excellent dashboard for radio users.  Visit https://www.swpc.noaa.gov/communities/radio-communications